CVE-2021-27343Public exploitNetwork attack vector

Sensitive-information disclosure via out-of-bounds DER read

Published Apr 6, 2021 · Updated Aug 3, 2024

Buffer overflow in SerenityOS LibCrypto allows remote attackers to read sensitive process data by parsing a crafted RSA key. Crypto::der_decode_sequence reads one byte beyond a two-byte heap allocation while decoding the crafted ASN.1 DER sequence. No authentication or user interaction is required; only confidentiality impact is documented, and code execution is not established.

CVSS severity7.5
High
EPSS probability1.67%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Buffer overflow in SerenityOS LibCrypto allows remote attackers to read sensitive process data by parsing a crafted RSA key. Crypto::der_decode_sequence reads one byte beyond a two-byte heap allocation while decoding the crafted ASN.1 DER sequence. No authentication or user interaction is required; only confidentiality impact is documented, and code execution is not established.

The record

CVE
CVE-2021-27343
Published
Apr 6, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-120
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 6, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

5.0NVDAV:N/AC:L/Au:N/C:P/I:N/A:N
7.5NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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